OZ 250 valve springs

[ozconv]

When I bought my cam from Mike at CI I also ordered a set of 289 valve springs. I am planning to use an OZ 250 head that appears to have larger than stock OZ valves (the valve stems are the larger OZ size but the intake is 1.77" and the exhaust is 1.476"). I removed one of the OZ valve springs to compare it to the 289 springs and it appears to be significantly larger and beefier. The wire diameter is about the same but the OZ springs have both a taller free height and a larger diameter to the wound coils. The shoulder on the valve spring seat that is cast into the head is also too large for the 289 springs to fit over. I bought a valve spring pressure gauge to compare the 2 for installed and open pressure but have not done so yet. If I am going to use the 289 springs, I guess I will have to have the valve seats machined. The head has already been checked out including hot tanked, checked for cracks and surfaced about 0.030" to get the chambers to 52cc's and is in decent conditions as is so I was planning to use the current valves, retainers, etc. Has anyone else with an OZ head run into this issue??

 

[CobraSix]

You should check your valve stem sizes against stock 200 valve stems.

When I got my OZ head, Mike had his local machine shop rebuild it with new stems and valves, all oversized 200 valves, but US spec so I could get replacement parts easier. It is something I asked him to do. There may be the chance yours has already had this done.

I'm using the springs that came with my Comp Cam kit.

 

[ozconv]

Mine are the larger 11/32 diameter OZ valve stems but are larger (1.77 intake, 1.476 exhaust) than what should be stock. The springs are way different and significantly larger than the 289 springs Mike sent me and the cast shoulder that the bottom of the spring fits over is too large a diameter for the 289 springs. I will try to take some pics and post a link to show what I am talking about. I also need to measure the strength of the springs at the installed closed length as well as open length and see how they compare to the 289 springs.

 

[CobraSix]

Have you tried some stock US 200 springs for fit?

I'm not sure about 289 springs versus 200 springs.

 

[ozconv]

I finally got some pictures comparing the springs that came with my OZ head to the 289 springs from CI. The 289 springs are the smaller ones on the right. I tried to measure the spring force at the installed (closed hieght) and open hieght using a valve spring pressure gauge and my drill press. The OZ springs had more pressure at the installed (closed hieght) but the 289 springs seemed to have about 20 lbs more at the open hieght. I need to recheck as I am not sure about my accuracy
[img=http://img192.imageshack.us/img192/9760/oz250head015.th.jpg]
[img=http://img641.imageshack.us/img641/6622/oz250head014.th.jpg]

The issue with installation is that the 289 springs will not fit over the boss on the valve spring pocket.

[img=http://img638.imageshack.us/img638/3346/oz250head017.th.jpg]

Has anyone else with an OZ head had this issue??

 

[falcon1963]

Since, you have 11/32 valve stem diameter, use springs & retainers from a small block chevy.
You need to measure your current installed valve spring height & use a spring that will have at least 90-100# seat pressure.
Call comp cams & they will hook you up with the right combination.
Do not use the stock ford 302 springs cause they will not do the job. Falcon Man